Mine too (build date Oct 17, 2013) behaves similarly w respect to lifting off brake and closed throttle. I don't know if I've ever been in a situation to effectively notice the hill assist.I have read most of the threads about the DCT and its problems and some of the features like Hill Assist, etc.
One thing that seems like people say a lot is that the car wont glide forward slowly with no throttle(just letting off the brake) like a conventional automatic. Well mine DOES act like that in regard to the slowly moving forward on a flat road and a small incline. I can edge up to a light just like any other automatic I have ever used. I know that Hill Assist is working on steeper hills cause I can feel the brake pedal pop. I am used to it cause my former Xterra did the same thing on steep inclines. But even after the hill assist lets go it will usually maintain position unless its pretty steep.